Method of making dies



F. R. STAFFORD.

METHOD OF MAKING DIES.

APPLICATION FILED JUNE 13. 19:].

Patented Sept. 2, 1919;

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A T TORNE Y8.

FRANK R. STAFFORD, OF PHILADELPHIA, PENNSYLVANIA.

METHOD or MAKING DIES.

Specification of Letters Patent.

Patented Sept. 2, 1919.

Original application filed August 22, 1916, Serial No. 116,346. Divided and this application filed June 13,

' 1917. Serial No. 174,567.

To all whom it may concern:

- 1 Be it known that I, FRANK R. STAFFORD, a

citizen of. the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Methods of Making Dies, of which the following is a specification, reference being had therein to the accompanying drawing.

My invention comprehends a novel method of making dies.

Ancillary features of invention and improvement will suificientlyappear from the detailed statement hereinafter.

- This application is a division of my prior I punch holder. .25-

' Fig. 3 represents in side elevation the die punch holder seen in Fig. 2, the views being taken 90 apart.

Fig. 4 represents a transverse section of the punch holder seen in Figs. 2 and 3.

Fig. 5 represents a bottom end view of the punch.

Fig. 6 represents a plan view of a die and its holder cooperating with a trimming punch. I

Fig. 7 represents a section on line 7-7 of Fig. 6.

Fig. 8 represents in perspective one type of an article which may be formed.

Figs. 9, 10 and 11, showstages in the formation of the unit die of Figs. 6 and 7.

It will be understood that the article shown in Fig. "8 is selected for purposes of illustration only, and that the shape and proportions of each die may be varied according to its uses, without departing from the in- .vention. The specific form of article and the specific form and arrangement of the set of tools illustrated and described herein, are for drop forging, on hot metal, the particular metal in this case being iron or steel;

ing, as required in the manufacture of such articles as jewelry, and many others.

In Fig. 1, I have shown a pair of drop forging dies 22 and 23, each containing a straight figure having a sectional contour corresponding exactly to'the outside contour of the article. These dies are secured in a press in the position shown and operate upon a bar of metal to produce the trimming punch 24 shown in Figs. 2, 3 and 4.

Figs. 6 and 7 show a working trimming die. The die proper 25 is carried on a body 26, has beveled sides 27 and is held in place by a clamping plate 28. It has a central opening 29, and its inner walls are first beveled at 30 and then at their upper edges formed with straight sides 31. A punch fits accurately within the edges 31, and in operation is secured above the same in the ress.

The die of Figs. 6 and 7 is forme also in the hyraulic press or equivalent machine. The first blow or operation causes the metal to flow into the shape shown in Fig. 9, the second forms the shapeof Fig. 10, and the third clears out the central opening, trims oif the outer flash, and forms the central open ing with the proper bevel 30 and straight cutting edges 31. The shape as shown in Fig. 11 is then pickled and tumbled to remove the scale left by the hot forging, and is compressed in the hydraulic press between complementary dies shaped to receive it, under heavy pressure, producing absolutely accurate dimensions and shape, and a glass finish. The die is then hardened and its base and top or crown are ground, with 'or without rehardening, giving the finished tool, ready for clamping onto its body as shown in Fig. 7. The die body of Figs. 6 and 7 is inserted in a groove in the bed plate of the press, and has its opposite edges beveled to fit undercut bevels in said groove. One side of the channel in the press is fitted with asteady-pin 38, and the corresponding side of the beveled edge of the body of the die is notched to fit said pin. There is enough clearance between the opposite edge of the die and the opposite dovetail of the slot to take a key, which is driven in tightly to hold the'die' in position. When this key is withdrawn, the die may be inserted, pressed over against the pin, and when itis thus centered and steadied by the-pin,the tapered key or keys may be inserted from one or both ends of the slot so that the'die is not only firmly held in the groove, but is I solidly pressed against the pin so that it is accurately and continuously centered. K

This die has been described and is indicated in the drawing with its end surface or headaplainfl I have found it advantageous in some casestoserrate this, so that the edge allaround the central opening 29 is fluted or serrated instead of plain. In order to attain this. end, the flutings are onradial linesconverging approximately to a point at the center of the opening (the die being .COIlSldGI'GCl in plan as shown in Fig. 6.) The die, upon which the article rests, while a punch is run through its central opening, is struck up in the same manner as the die shown in Figs. 6 and 7 except that the die has the shape of the article impressed in it, and its edge out out-to form'an openinginside the internal contour ,of-thearticle. This wouldbe diflicult to make, as would any of these shapes, many other manner than by a master punch.

1 The punch shownin FigsQQ to inclusive cooperateswiththe trim die of Figs. 6 and 7, :the article; being forced through "the .dle by the punch, and the punch being provided not only with the oval body portion 24, but with a lateral projection or tongue 24 matchinga corresponding opening 81 in the die, toforce down the projecting part of the article. (See Fig. 8.) The piercing die, on the other hand, has its inner edges the sizeand shape of the initial opening inothe article, which of course hasno projection but is simply oval. All around these edges an intaglio impression of the article is formed, the inner edge being left sharp, and

the depth of the impression being one-half the depth of the article. The punch which "goes with this die isv constructed in a similar manner to the punch of Figs. 2 to 5, but has its cross section oval without the tongue or projection 24*. This punch, and also the punch shown in Figs. 2 to 5 is made of sufficient length to permit of considerable grinding ofi" and wearing down, and they may both be, and in practice I contemplate having them, fluted or corrugated on' their ends, so that while their cross section contours Will be necessarily the same as those of the article, their 7 cutting edges will be -cor-,

rugated or waved. I

I have not illustrated or described specifically the tools employed in forming uptheting trimming die as illustrated in Figs. 7 to 11 inclusive, but I may state generally that as hereinbefore stated the metal is forged heated, being swaged up by suitable dies and punches in successive operations I the forms shown respectively in Figs. 9, 1O, 11 and 7, in the order given. The value of this -method lies in its utilization of the principles of metal flow, so that the metal of the finished product is homogeneous, uniform in grain and texture, without'strain or abnormal crystallization,- and capable of being uniformly hardenedthroughout and given a very high finish, resulting in increased efficiency and long life. At the same time, it will be obvious fromthe description'that the cost of. production is I low and the interchangeability of .theind-ividual dies is per feet, because they are mathematically identical in shape and dimensions.

Having thus described my invention what I claim and desire to secure by Letters'Patent is .z

1. The method of producing interchange able unit trimming dies which consists in first forging a cup with a thin bottom: and thickened sides, then further causing the metal to flow into finished shape with inner walls tapering-to .the bottom, and finally punching out the bottom so as to leave a cutedge. ..1 1 2. The methodof producing interchangeable unit. trimming dies-which consists in first forging a cup with a thin bottom, and

tapered sides, and then punching out the bottomto form a cutting edge, and finishing the side walls.

3; The method of producing interchange able unit trimming dies which consists in first forging a cup with thin bottom and tapering sides having their upper edges exby means of a punching die of finished shape punching out the bottom to form a cutting edge, and at the same operation forcing up 7 the metal around the punch and in the die so as'to finish the walls with precision. i

5. Themethod of producing interchangeable unit trimming dies which consists in first forging the die with the central opening and cutting edge therein; second treating as by pickling and tumbling to remove the scale left by-the hot forging; and third compressing the same in a press between complementary dies under heavy pressure to produce accurate dimensions and shape and a glass finish. a

6. The method of producing interchangeable unit trimming dies which consists in first forging the die with the central opening and cutting edge therein; second treating as by pickling and tumbling to remove the scale left by the hot forging; third compressing the same in a press between complementary dies under heavy pressure to pro duce accurate dimensions and shape and a glass finish, and finally hardening the die and grinding its base and top or crown.

In testimony whereof I aflix my signature.

FRANK R. STAFFORD.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

